1. Technical Field
The present disclosure relates to a radar device installed in a moving object (e.g., a vehicle), the moving object in which the radar device is installed, and a moving object speed detection method of detecting a speed of travel of the moving object.
2. Description of the Related Art
There are known radar devices which receive returning signals reflected off of a target at an antenna array, and measure the phase difference of the reception signals received by reception antenna elements, thereby estimating a direction of arrival of returning signals from the target over a wide angle range.
Examples of related art relating to installing a radar device capable of wide angle range measurement in a moving object (e.g., a vehicle), and detecting the position and relative speed of a target in the perimeter, include Japanese Unexamined Patent Application Publication No. 2004-177289 and Japanese Unexamined Patent Application Publication No. 2010-043960.
A target speed calculating device shown in Japanese Unexamined Patent Application Publication No. 2004-177289 calculates, based on a radar device measuring relative speed Vr and an azimuth θr as to a target vehicle ahead of a subject vehicle, a vehicular speed sensor that detects vehicular speed Vs of the subject vehicle, and an azimuth θr of the object (target) which is to be measured by the radar device, an angle θ between the direction of travel of the vehicle and the azimuth of the object (=θr+θs). The speed Vo of the target is corrected to Vo=Vs×cos(θr+θs)−Vr at a computing unit, based on the relative speed Vr, speed Vs of the vehicle and the angle θ. Note that the angle θs between the direction of travel of the subject vehicle and the axle is calculated one combination out of the combinations “rudder angle sensor, vehicular speed sensor, and yaw rate sensor” and “vehicular speed sensor and side acceleration sensor”.
Also, a vehicular moving state detection device shown in Japanese Unexamined Patent Application Publication No. 2010-043960 uses multiple side monitoring radar devices to identify stationary objects. Specifically, based on detection values of azimuth and relative speed for each electromagnetic wave reflection part, the vehicular moving state detection device uses an azimuth φ of an electromagnetic wave reflection part situated closest to the subject vehicle out of the electromagnetic wave reflection parts, and a relative speed Vd0, so as to correct the measurement value of relative speed Vd0 at the electromagnetic wave reflection part to Vd=Vd0×cos φ. In a case where the relative speed Vd after correction is equivalent to the detection value is equivalent to the detected value VO of the onboard speedometer, an aggregate of electromagnetic wave reflection parts is identified as being a stationary object. The azimuth φ of the electromagnetic wave reflection part is an azimuth with reference to the frontal direction of the subject vehicle (φ=0).